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The aim of this investigation is to determine the concentration of Limewater.

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Introduction

Orehra Mahmood- Limewater practical. Aim: The aim of this investigation is to determine the concentration of Limewater. Plan: I am required to find the concentration of a sample of Limewater solution in g dm3 Ii is vital for me to design my own experiment and choose a range of appropriate equipment and apparatus. I am provided with 250 cm3 of Limewater, which has been made such that it contains approximately 1g dm3 of calcium hydroxide. Also available is hydrochloric acid, which has a concentration of 2.00 mole dm3, however this concentration is too much though, so it is necessary to dilute it to an appropriate diluted volume. The indicator will be supplied to me-, which is known as methyl orange. Slaked lime dissolved in water is called Limewater. Calcium oxide reacts violently with water to produce calcium hydroxide (slaked lime) Addition of further water to Calcium hydroxide produces the saturated aqueous solution known as Limewater. In order for me to establish the concentration of the Limewater it is necessary to react the Hydrochloric acid with the Limewater. ...read more.

Middle

So if I were to use the phenolphthalein indicator then the end point (colour change) would be reached before the equivalence point (when the chemicals, acid-base break up). Calculations:- In order to work out the amount of molar of acid I will require to carry out some calculations. I need to work out how much I will need to dilute the acid until it is at the appropriate dilution for my investigation. Here are the calculations that I carried out to work out the dilution I required for my acid:- Moles = mass/molar weight (Mr)= 1gdm-3. Ca (oh) 2 40+ (16 +1) x2 =40+ 34 =74g =1gdm- 3/ 74g/ mol =0.0135 mol/ dm-3 = 25 x 0.0135/ 1000 = 0.00034 mols. Ca (OH)2 + HCL - CaCl2 + 2H20. Balance the equation above to get--- 1 mol of Ca (OH) 2 = 2 mols of HCL. 0.00034 x 2 = 0.0007 mols. Mols = volume / 1000 x morality, Morality = mols x 1000 / volume. ...read more.

Conclusion

I want to dilute the acid to 0.1 moles, so I pipette 25.0cm3 of HCl from the original bottle and place it in the 500cm3 volumetric flask. Then I add 475cm3 of distilled water to the same volumetric flask, I measure the amount of water by looking at the graduated mark on the flask and fill until the 500cm3 mark. Once I have obtained the correct concentration of Hydrochloric acid I can precede to the rest of the experiment. First I must set up the apparatus as I have indicated in my diagram. I will be using 25.0cm3 of Limewater and I will transfer it into the conical flask using a 25.0cm3 pipette. It is also important to add the indicator into the conical flask so that the neutralisation point can be obtained, where five drops of methyl orange should be appropriate. When the indicator is added the colour of the solution is light, clear, orange and this should turn to pink by the end of the titration. In order to obtain consistent and reliable results it is necessary to repeat the experiment several times. After this it the results must be noted in a table ...read more.

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